SU meets SatAM
by Kitty Craft
Summary: When Sonic is having nightmares and is turning into a dark being every night, the Sonic Underground go to the Oracle who sends them to another world. When arriving there, they meet some people from Knothole and another Sonic! Two Sonic's what can go wrong? Can SU Sonic, Sonia, and Manic return home? Will they find their mother? Will Robotnik be stopped? (SatAM SU Crossover)
1. New World, New Life, Two Sonics!

**Sonic Underground meets Sonic SatAm**

 **Chapter 1**

 **New World, New Life, Two Sonics?!**

-Robotropolis (Sonic Underground) March 14th 3232 12:00 AM-

It was a dark and gloomy night in the Underground Freedom Fighters HQ, everyone was having sweet dreams, except for one blue hedgehog.

 _Sonic was running to save Sonia and Manic from Robotniks roboticizer, but when he got there, Sonia and Manic where mindless robots. Sonic was boiling with anger, his fur was turning back, and his pupils were white._

 _"WHAT DID YOU DO?!" Sonic's voice was darker, he was emitting dark energy._

Sonia and Manic both woke up to Sonic screaming darkly, they got out of bed to gasp in horror. Sonic's fur was pitch black, his pupils were gone, and he was covered with dark energy.

"S-Sonic?!" Sonia was backing up from complete shock, _'what happening to Sonic? Why is he like this'_ She thought.

"Sonic, bro... Its us, Sonia and Manic" Manic was moving towards the black hedgehog.

"Sonia? Manic?" Sonic's voice was now darker, Manic knew it had to do with a nightmare. Manic was now right in front of Sonic, he placed a hand on Sonic's shoulder. Sonic's eyes then faded back, his fur faded back to its original royal blue, and all of the dark energy went away. Sonia and Manic sighed with relief, they knew Sonic had been having nightmares lately about him losing them and or their mother, and each night he has been turning into this dark being. The rest of the freedom fighters don't know about Sonic's problem yet, who knows what would happen. Sonia and Manic stayed by Sonic's side for the rest of the night, so Sonic knew he have to go through this alone. The next day, Sonic, Sonia, and Manic decided to go to the Oracle of Delphius and ask him what's wrong with Sonic. About 3 hours later, the three hedgehogs reached the Oracle's cave.

"Hello young hedgehogs" The Oracle greeted the triplets. "What seems to be the matter?" Sonia stepped forward.

"Its about Sonic" The Oracle could hear sorrow in the females voice, he knew what was wrong.

"You came about his transformations didn't you?" Sonia and Manic nodded, they both stepped back and pushed Sonic forward.

"Each night, I have the same nightmares about losing Sonia, Manic, and sometimes Mom, and each night I would always turn into a dark being" Sonic looked at the ground, he hated that form so much, he even hurt his own brother the first time it happened. The Oracle thought for a moment.

"I may have an idea that will help you in two ways, stopping Robotnik and having an end to Sonic's transformations" The triplets knew what The Oracle had in mind.

"You're going to send us into another dimension aren't you" Manic said, The Oracle chuckled

"You are right young hedgehog, but I have a warning. This other world is almost the same as this one, you'll know the difference when you get there, I also will let you keep your powers because of this." The Oracle informed. "I wish you three good luck" After The Oracle finished, he opened a portal and the three hedgehogs were sucked in.

"AHHHHHHHHHHH!" Sonic, Sonia, and Manic where falling into nothing but darkness, then everything went black.

-Unknown Location March 15th 3232 9:00 PM-

Black, That's all that Sonia saw, Blackness surrounding her. She felt a hot, wet, rag on her forehead. She opened her eyes and sat up, she looked around to find herself in a hut. Just then she saw a rabbit with both her legs and her left arm roboticized walk in with a tray of food.

"Oh, Your awake, My names Bunny Rabot" The rabbit said, handing Sonia the food.

"Thank you, My names Sonia, can you please tell me where I am?" Bunny smiled.

"Of course sugar! You're in Knothole, It's where one group of Freedom Fighters are" This confused Sonia, there are more Freedom Fighter groups besides her group?

"Thanks, But I didn't know there were other Freedom Fighter groups"

"Well we didn't either until a while back" Sonia sighed, where were her brothers... _'Wait... MY BROTHERS!'_

"WHERE ARE MY BROTHERS?!" Bunny looked at Sonia with confusion.

"You were passed out in the middle of the forest by yourself, if you'd like, we can help you look for your brothers" Sonia gasped.

"You'd do that for someone you've just met?" Bunny nodded. Sonia then jumped up and hugged Bunny. "Thank you so much!"

"Your welcome, now get some sleep"

-The Great Forest March 16th 3232 12:00 AM-

SatAM Sonic was walking around the forest, He had heard a scream come from the forest that almost sounded like his voice. He was walking around with a flashlight for a few minutes, then he saw two hedgehogs, One emerald green, the other black as the night sky with pure white eyes.

"Come on bro, snap out of it! It was a nightmare! I'm fine and wherever Sonia is, I'm sure she's fine too!" The emerald hedgehog said, trying to calm the black hedgehog down.

 _'Sonia? Isn't she that female hedgehog that was passed out in the forest?'_ SatAM Sonic thought. _'These must be her brothers'_ Just then the black hedgehog's quills and fur were fading into a royal blue and his eyes were fading back. _'If so... WHY DOES ONE OF THEM LOOK LIKE ME?!'_ The green hedgehog turned around and looked at SatAM Sonic with shock. Then they all screamed.

-The Great Forest March 16th 3232 12:03 AM-

Sonia, Sally, Bunny, Roder, and Antoine were running around the Great Forest to find SatAM Sonic, when they found SatAM Sonic, they stopped and there eyes widened with shock, They saw a green hedgehog, and two Sonic's! What surprised them the most is when Sonia hugged SU Sonic and the green hedgehog.

"There you two are, I was so worried about you!" Sonia cried.

"Yo, Chill sis, were fine!"Manic said trying to calm his sister down. SU Sonic looked up at Sally, Roder, Bunny, Antoine, and SatAM Sonic.

"Uh... Sonia? Who are they?" SU Sonic asked. Sonia turned around to see the Knothole Freedom Fighters eyes as wide as saucers.

"Oh, They are the Knothole Freedom Fighters" Sonia replied.

"Can someone please tell me whats going on?!" SatAM Sonic yelled, Manic opened his mouth to say something but was cut off when SU Sonic spoke.

"Were from another dimension" SU Sonic told the Knothole Freedom Fighters.

"Whats this other dimension like?" Roder asked

"Well, its almost like this one" Manic replied.

"So, there's a royal family?" The triplets nodded.

"Its a long story..." SU Sonic said, SatAM Sonic crossed his arms.

"We've got time"

"Well..."

 _ **Flashback**_

 _ **...It was a dark and stormy night, it was the year 3218. Queen Aleena had giving birth to triplets, 2 boys and a girl. One day The Oracle of Delphius had giving the Queen a prophecy.**_

 _ **"One day you will reunite with your children to create the Council of Four!" But for the prophecy to be fulfilled, she had to give up her children. The girl went to a rich family and they taught her to be a proper lady, one of the boys went to a middle class family but when he was five he had to leave to his Uncle when his family was taking away by Robotnik, the last boy was raised by thieves and they taught him how to be a thief, pick locks, and hack computers. When they were 13, the Oracle told one of the boys about his past and how he was a prince and that he had a brother and a sister.**_

 _ **"In order to find them, you must play a song from your heart!" So he did. Then the three where reunited and the girl and the other boy joined the resistance so all 3 of them could find their mother and defeat Robotnik. One year later one of the boys started having nightmares about losing his brother, sister, and or his mother, causing a transformation. The only way to snap him out of it is to calm him down. This was happening for about a week so they went to The Oracle to ask for help, he then sent the 3 of them to another dimension"**_

 _ **End Flashback**_

When Sonic finished, The Knothole Freedom Fighters eyes were wide with shock. The first to speak was Antwan.

"You are telling me zhat this _fuel_ is a prince?!" The triplets nodded. By the time the story was over they were all in Knothole. SU Sonic touched his medallion and it turned into a guitar

"How about a song?" Sonia and Manic nodded and turned their medallions into a keyboard and drums.

"One, two, three, four!"

 **"Fight Song - Male Vocal Cover - Rachel Platten" By Caleb Hyles**

 _Like a small boat_

 _On the ocean_

 _Sending big waves_

 _Into motion_

 _Like how a single word_

 _Can make a heart open_

 _I might only have one match_

 _But I can make an explosion_

 _And all those things I didn't say_

 _Wrecking balls inside my brain_

 _I will scream them loud tonight_

 _Can you hear my voice this time?_

 _This is my fight song_

 _Take back my life song_

 _Prove I'm alright song_

 _My power's turned on_

 _Starting right now I'll be strong_

 _I'll play my fight song_

 _And I don't really care if nobody else believes_

 _'Cause I've still got a lot of fight left in me_

 _Losing friends and I'm chasing sleep_

 _Everybody's worried about me_

 _In too deep_

 _Say I'm in too deep (in too deep)_

 _And it's been two years_

 _I miss my home_

 _But there's a fire burning in my bones_

 _Still believe_

 _Yeah, I still believe_

 _And all those things I didn't say_

 _Wrecking balls inside my brain_

 _I will scream them loud tonight_

 _Can you hear my voice this time?_

 _This is my fight song_

 _Take back my life song_

 _Prove I'm alright song_

 _My power's turned on_

 _Starting right now I'll be strong_

 _I'll play my fight song_

 _And I don't really care if nobody else believes_

 _'Cause I've still got a lot of fight left in me_

 _A lot of fight left in me_

 _Like a small boat_

 _On the ocean_

 _Sending big waves_

 _Into motion_

 _Like how a single word_

 _Can make a heart open_

 _I might only have one match_

 _But I can make an explosion_

 _This is my fight song (Hey!)_

 _Take back my life song (Hey!)_

 _Prove I'm alright song (Hey!)_

 _My power's turned on_

 _Starting right now I'll be strong (I'll be strong)_

 _I'll play my fight song_

 _And I don't really care if nobody else believes_

 _'Cause I've still got a lot of fight left in me_

 _No I've still got a lot of fight left in me_

The medallions turned back to normal and everyone was cheering for the three hedgehogs.

"That was awesome!"SatAm Sonic congratulated.

"Thanks, we do this all the time" SU Sonic high-fived SatAM Sonic. This was a start to a way past cool new friendship


	2. He plans to do what? !

**Sonic Underground meets Sonic SatAM**

 **Chapter 2**

 **He plans to do what?!**

-The Floating Island (Sonic Underground universe) March 16th 3232 12:00 PM-

On The Floating Island, A certain Echidna was waiting for a message from the Freedom Fighters, The Sonic Underground to be precise. What Knuckles didn't expect was a visit from Cyrus the Lion.

"Hey Cyrus! What are you doing here?" Knuckles asked, he then saw Cyrus' worried expression. "Did something happen?" Cyrus grabbed Knuckles by the shoulders and shook him violently.

"Sonic, Sonia, and Manic are gone!" Cyrus yelled. Knuckles pried Cyrus off of him.

"What do you mean they're gone?"

"They're gone is what I mean! They left to go see the oracle but they haven't returned yet!"

"How long have they been gone for?"

"They left two days ago!" Knuckles started to get worried. He has known the Sonic Underground for a while now, and he knows how long a visit to the oracle takes. They have been gone for far too long, something has happened, something **BAD**. Knuckles then started fearing for the worst.

"We don't know what happened, so let's wait awhile, If they don't return we can assume that they are dead or worse." Knuckles put a hand on Cyrus' shoulder. "We just have to have faith in them" Cyrus sighed.

"You're right, we just need faith that they are okay"

-Knothole Village (SatAM universe) March 16th 3232 12:00 PM-

It's been a whole day since SU Sonic, Sonia, and Manic had arrived to this parallel universe, and they are still getting used to things around Knothole. But they have been getting along with everyone, SU Sonic has taken a liking to Tails, he just like how he was when he was younger, adventures and filled with determination but also very shy around new people. It took Tails awhile to get used to two Sonics, but he really enjoys their company.

"...Then I said "game over Robuttnik!" SU Sonic said as he finished his story. Tails and SatAM Sonic's eyes went wide, the story that they had just heard was so amazing and unbelievable.

"You actually were stuck inside a video game?!" Tails asked with disbelief.

"You bet I did, almost died too, almost" SU Sonic assured him. SatAM was about to ask about how that was actually possible, but then Sally came in running towards SatAM Sonic.

"Sonic! It's Charles! He's here!" Sally said through pants. SatAM Sonic's eyes widened and he grinned.

"Uncle Chuck? He's here!" SU Sonic couldn't believe it, the Chuck of this universe was alive, and not roboticized.

"C-Chucks here… H-He's okay….." Sally and SatAM Sonic looked at each other with concerned eyes. They knew that Chuck was roboticized in both universes, but they're Chuck has a free will, they don't know how to tell SU Sonic that.

"Uh… sort of" SU Sonic was confused.

"What do you mean 'sort of'?"

"Hes….. Kinda…. A robot…."

"You said he was here! How can he be here if he's roboticized?!"

"Because he has a free will" Sally had said. SU Sonic's eyes widened. ' _How does their Uncle Chuck have a free will? I know me and my siblings can make a roboticized citizen have a free will, but that's only for 5 minutes, did they find a way to permanently give the roboticized people their free will back?'_

-Roder's Workshop (SatAM universe) March 16th 3232 12:15 PM-

"So you're saying that Robotnik is planning to do what?!" Roder was in total disbelief, Robotnik is evil but he isn't that evil, is he?

"He's planning on making a machine that will kill every living thing unless you surrender the power rings to him" Chuck explained. Robotnik has done some really bad things in the past, but he hasn't gone low enough to **kill people** to get what he wants, it's too unbelievable, but they were all looking right at the blueprints for this killing machine, it was right in front of them.

"I don't believe it" SatAM Sonic said holding his head. SU Sonic's had made his hands into fists and punched the wall, Robotnik has gone too far, even if it's not his Robotnik, it had to stop ' _he has to die…..'_. Black electricity was surrounding SU Sonic and his quills was a few shades darker. Manic put a hand on SU Sonic's shoulder, he knew what his brother was thinking, he had to stop him from thinking it.

Chuck was still trying to get his head around their being two Sonics, he was given a short explanation on it, but it wasn't a big deal, it was bound to happen at some point. But he knew they were sent to this universe for a reason, he thinks that reason is to help them stop Robotnik from killing everything.

 **Authors Note: OOOOOOOOOOOH MY GOODNESS! This took way too long! - Sorry for the wait, I had sooooo much school work (Still do) and I had 5 beginnings to choose from, then I realized my mistake from last chapter… I made both Sonics high 5…. I destroyed the multiverse… So as you can see I didn't choose the destroyed multiverse beginning. Anyway the next chapter won't take so long to make, so see you later bye~!**


	3. Mission: Infiltrate Robotnik's base

**A/N: before the chapter starts, I would like to say that I'm sorry that this took so long for me to post. A lot has been happening lately and it caused me not to update, and I am truly sorry. But when I read this comment from a guest, it made me smile and it also gave me the courage to finish this chapter even though I don't have a computer to use. So I had to struggle to use an IPad to type this WHOLE chapter. I'd like to thank this guest who wrote this comment: "You have NO idea how excited I was when I saw you had updated, like oh my gosh. I was literally bouncing off the walls! You are an amazing writer and I love this fic. Keep up the amazing work!" It really made my day and also this chapter, and I'd also like to thank all of my readers. It makes me happy to know that someone is reading my crappy stories and actually liking them. Thank you everyone for all the support, and without further adu…**

 **SU meets SatAM**

 **Chapter 3**

 **Mission: Infiltrate Robotnik's base**

-Knothole Village (SatAM universe) March 16th 3232 12:17 PM-

Robotnik has gone too far, he has done some pretty bad things in the past, but this is going to far, and SU Sonic hated it. 'Robotnik plans on killing people, living people, just so he can get what he wants!'. SU Sonic could feel the dark energy surrounding him, but he didn't care, Robotnik has to be stopped, he can't be worrying about himself, he has to worry about what the others. SU Sonic felt the comfort of his brothers hand on his shoulder, it was then when he realized that he had punched a hole through the wall. He shook his head and felt all of his anger leave his mind, he couldn't lose it now, not when he still has his family to support him.

"Are you going to be okay?" Manic asked with a concerned tone. SU Sonic nodded his head yes.

"Yeah I'm fine, but we need to make sure that this killing machine is never completed" All of them nodded, SU Sonic was right, if Robotnik finished his creation it would be the end for everyone. "We need to sneak into Robuttnik's fortress and find out where this machine is being built and blow it up!"

"Sonic's right, that's exactly what we need to do" Sally said as she got out Nicole. "We will be in teams of four" She pulled up a map of Robotnik's base. "Roder, Bunny, Antwan, and I will go and find out where this machine is being built, Sonia, Manic, and both Sonic's will go and destroy the factory that it is being built in."

"We will also go and delete all of the folders and documents for the machine so Robotnik won't go and build it again" Roder finished and he handed SatAM Sonic a walkie talkie.

"Robotnik's base is going to be harder to infiltrate than ever, so we need to be ready for anything that he throws at us" Manic explained. Everyone nodded, they knew that Robotnik probably has Swat-bots everywhere, to make sure that they don't get their hands on the information they need.

-Robotnik's fortress (SatAM universe) March 16th 3232 12:30 PM-

Everything was set, all they needed to do was sneak into Robotnik's base, find out where this killing machine is being built, delete all of Robotnik's data, and destroy the machine, seems easy enough. And everyone was ready, everyone except Antwan.

"Mi princess, zis seems to dangerous, yes? Let us turn around" Antwan said, being the scaredy cat that he is.

"Antwan, If we don't do this, we will all die" Sally replied."Nicole, anything on where the machine is being built?"

"I'm on it, Sally" Nicole said as she was looking through Robotnik's database. "I'm sending the coordinates to Sonic's group now"

"Great job Nicole!" Roder said excitedly.

-Robotnik's Factory (SatAM universe) March 16th 3232 12:40 PM-

SU Sonic, SatAM Sonic, Sonia, and Manic had arrived at the factory, with hopes to destroy the killing machine. But what they found was an abandoned warehouse.

"Are you sure this is the right place Manic?" SU Sonic asked his brother.

"I know how to work coordinates Sonic!" Manic replied.

"Okay, just checking" Manic rolled his eyes and entered the building, with the rest of the group following.

"Maybe there's a secret door somewhere" Sonia exclaimed. SatAM Sonic shook his head.

"Not likely, Robuttnik is smart, but not that smart" Everyone nodded their heads in agreement. As they turned around to leave they saw that the doors were locked shut.

"It looks like you've fallen into my trap" They all turned to see Robotnik and a horde of Swatbots.

"This isn't good" both Sonic's said.

 **A/N: I'm sorry this is short, but I have writer's block :D. yay. Anyways I'm also sorry for the long wait for this short thing but again writer's block… I didn't want you guys to wait any longer though so here's something. Anyways thank you for reading and I will see you in the next (maybe) exciting chapter of SU meets SatAM! Bye~!**


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